Previous studies on Korean EFL learners’ motivation focus on investigating the applicability of the results of previous research on L2 motivation to Korean EFL context. From the perspective of L2 motivation as a dynamic construct that is context- and time-dependent, a recent study explores the underlying dimensions of Korean high school students’ motivation in learning English based on the responses of students enrolled in 2012. The present study expands the recent study by investigating the relationship between Korean high school students’ motivation and their English proficiency. Based on the survey responses of 452 high school students enrolled in 2014, 5 factors (Globality, Students’ taste, English as a lingua franca, Futurity, and Schooling) consisting of the students’ motivation are examined in relation to students’ English proficiency scores. The results show that Students’ taste and Futurity are positively related to students’ proficiency scores while Schooling is negatively related.